Laser catheter with use of reflected light to determine material type in vascular system

ABSTRACT

Apparatus and methods for determining a type of a material in a region within a vascular system of a patient and/or a distance to the material are provided. At least one source fiber is provided that supplies light from a light source to a region within a vascular system of a patient. At least one return fiber is provided to receive light reflected from the region within the vascular system. At least one controller is provided to determine at least one property of the region within the vascular system from the reflected light, and to determine a type of a material in the region within the vascular system and/or an indication of a distance to the material. Techniques such as laser ablation may then be performed based on the determined material type and/or distance to remove unwanted buildup, deposits, etc., while avoiding harmful results such as tearing of tissue.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.14/586,529, entitled “LASER CATHETER WITH USE OF DETERMINED MATERIALTYPE IN VASCULAR SYSTEM IN ABLATION OF MATERIAL,” which is filed on thesame day as the present application and the contents of which areincorporated by reference herein for all that it discloses. The presentapplication is also related to U.S. patent application Ser. No.14/586,543, entitled “LASER CATHETER WITH USE OF REFLECTED LIGHT ANDFORCE INDICATION TO DETERMINE MATERIAL TYPE IN VASCULAR SYSTEM,” whichis filed on the same day as the present application and the contents ofwhich are incorporated by reference herein for all that it discloses.

FIELD

The present disclosure relates generally to medical devices, and, moreparticularly, to laser catheters used in treatment within a vascularsystem and the use of reflected light associated with a laser catheterto determine a type of a material within a vascular system.

BACKGROUND

Electrical leads, such as those used with pacemakers, defibrillators,etc., are implanted in the human vascular system and often experience abuildup of unwanted deposits thereon, such as plaque, calcified tissue,and the like. Additionally, human blood vessels often become occluded orblocked by plaque, thrombi, other deposits, emboli, etc., which reducethe blood carrying capacity of such vessels. Should a blockage occur ata critical place in the vascular system of a patient, serious andpermanent injury, and even death, can occur. To prevent damage toelectrical leads, and to prevent damage elsewhere in the vascularsystem, some form of medical intervention is usually performed when abuildup or significant occlusion is detected.

Laser-based catheter devices are often used to ablate such buildups orocclusions. Laser light is sent down optical fibers of a laser catheterto perform laser ablation and, in some cases, visualization of vascularstructure. Additionally, fluoroscopy presents a two-dimensional viewand, in cases where contrast agents are injected, provides indirectvisualization of vascular structure. Fluoroscopy is a procedure that mayintroduce undesirable radiation exposure and risks associated with theuse of contrast agents, and may also provide insufficient imaging orfeedback for clinicians to clearly understand the interface between thecatheter device and the vascular system. As a result, with a fluoroscopyprocedure, there is a risk of errors in determining whether or notcontacted tissue should be ablated, errors in determining how muchundesired tissue remains during or after ablation, and potentialovertreatment including tearing of tissue.

SUMMARY

These and other needs are addressed by the various aspects, embodiments,and configurations of the present disclosure.

According to one embodiment of the present disclosure, an apparatus fordetermining a type of a material in a region within a vascular system ofa patient may include a laser catheter and at least one controller. Thelaser catheter may be coupled to a light source and may include at leastone source fiber configured to supply light from the light source to aregion within a vascular system of a patient so as to illuminate theregion within the vascular system of the patient. The laser catheter mayalso include at least one return fiber configured to receive lightreflected from the region within the vascular system of the patient,where the reflected light may be indicative of at least one of atransmittance, a reflectance, an absorbance, and a scatteringcoefficient of the region within the vascular system of the patient. Theat least one controller may be configured to determine the at least oneof the transmittance, the reflectance, the absorbance, and thescattering coefficient of the region within the vascular system of thepatient. The at least one controller may be further configured todetermine a type of a material in the region within the vascular systembased on determining the at least one of the transmittance, thereflectance, the absorbance, and the scattering coefficient of theregion within the vascular system.

According to another embodiment of the present disclosure, an apparatusfor determining a type of a material in a region within a vascularsystem of a patient and a distance to the material may include a lasercatheter and at least one controller. The laser catheter may be coupledto a light source and may include at least one source fiber configuredto supply light from the light source to a region within a vascularsystem of a patient so as to illuminate the region within the vascularsystem of the patient. The laser catheter may also include at least onereturn fiber configured to receive light reflected from the regionwithin the vascular system of the patient. The at least one controllermay be configured to determine at least one property of the regionwithin the vascular system from the reflected light from the regionwithin the vascular system. The at least one controller may also beconfigured to determine a type of a material in the region within thevascular system based on determining the at least one property from thereflected light. The at least one controller may be further configuredto determine an indication of a distance to the material in the regionwithin the vascular system based on determining the at least oneproperty from the reflected light.

According to yet another embodiment of the present disclosure, a methodfor determining a type of a material in a region within a vascularsystem of a patient may include receiving an output from at least onereturn fiber of a laser catheter, where the at least one return fiberreceives light reflected from a region within a vascular system of apatient after at least one source fiber has supplied light to theregion. The reflected light may be indicative of at least one of atransmittance, a reflectance, an absorbance, and a scatteringcoefficient of the region within the vascular system of the patient. Themethod may also include determining the at least one of thetransmittance, the reflectance, the absorbance, and the scatteringcoefficient of the region within the vascular system of the patient. Themethod may further include determining a type of a material in theregion within the vascular system of the patient based on determiningthe at least one of the transmittance, the reflectance, the absorbance,and the scattering coefficient of the region within the vascular system.

According to another embodiment of the present disclosure, a method fordetermining a type of a material in a region within a vascular system ofa patient and a distance to the material may include receiving an outputfrom at least one return fiber of a laser catheter, where the at leastone return fiber receives light reflected from a region within avascular system of a patient after at least one source fiber hassupplied light to the region. The method may also include determining atleast one property of the region within the vascular system from thereflected light from the region within the vascular system. The methodmay further include determining a type of a material in the regionwithin the vascular system based on determining the at least oneproperty from the reflected light. The method may also includedetermining an indication of a distance to the material in the regionwithin the vascular system based on determining the at least oneproperty from the reflected light.

According to yet another embodiment of the present disclosure, anon-transitory computer-readable medium may include executableinstructions that when executed by one or more processors cause the oneor more processors to generate, based on light reflected from a regionwithin a vascular system of a patient after illumination of the regionwith light from a light source, at least one signal indicative of atleast one property of the region within the vascular system. Theexecutable instructions, when executed by the one or more processors,may also cause the one or more processors to determine, based on thegenerated at least one signal, the at least one property of the regionwithin the vascular system. The executable instructions, when executedby the one or more processors, may further cause the one or moreprocessors to determine a type of a material in the region within thevascular system based on determining the at least one property of theregion.

These and other advantages will be apparent from the disclosure of theaspects, embodiments, and configurations contained herein.

As used herein, “at least one”, “one or more”, and “and/or” areopen-ended expressions that are both conjunctive and disjunctive inoperation. For example, each of the expressions “at least one of A, Band C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “oneor more of A, B, or C” and “A, B, and/or C” means A alone, B alone, Calone, A and B together, A and C together, B and C together, or A, B andC together. When each one of A, B, and C in the above expressions refersto an element, such as X, Y, and Z, or class of elements, such asX₁-X_(n), Y₁-Y_(m), and Z₁-Z_(o), the phrase is intended to refer to asingle element selected from X, Y, and Z, a combination of elementsselected from the same class (e.g., X₁ and X₂) as well as a combinationof elements selected from two or more classes (e.g., Y₁ and Z_(o)).

It is to be noted that the term “a” or “an” entity refers to one or moreof that entity. As such, the terms “a” (or “an”), “one or more” and “atleast one” can be used interchangeably herein. It is also to be notedthat the terms “comprising”, “including”, and “having” can be usedinterchangeably.

The term “automatic” and variations thereof, as used herein, refers toany process or operation done without material human input when theprocess or operation is performed. However, a process or operation canbe automatic, even though performance of the process or operation usesmaterial or immaterial human input, if the input is received beforeperformance of the process or operation. Human input is deemed to bematerial if such input influences how the process or operation will beperformed. Human input that consents to the performance of the processor operation is not deemed to be “material”.

A “catheter” is a tube that can be inserted into a body cavity, duct,lumen, or vessel, such as the vasculature system. In most uses, acatheter is a relatively thin, flexible tube (“soft” catheter), thoughin some uses, it may be a larger, solid-less flexible—but possibly stillflexible—catheter (“hard” catheter).

The term “computer-readable medium” as used herein refers to any storageand/or transmission medium that participate in providing instructions toa processor for execution. Such a medium is commonly tangible andnon-transient and can take many forms, including but not limited to,non-volatile media, volatile media, and transmission media and includeswithout limitation random access memory (“RAM”), read only memory(“ROM”), and the like. Non-volatile media includes, for example, NVRAM,or magnetic or optical disks. Volatile media includes dynamic memory,such as main memory. Common forms of computer-readable media include,for example, a floppy disk (including without limitation a Bernoullicartridge, ZIP drive, and JAZ drive), a flexible disk, hard disk,magnetic tape or cassettes, or any other magnetic medium,magneto-optical medium, a digital video disk (such as CD-ROM), any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, a solidstate medium like a memory card, any other memory chip or cartridge, acarrier wave as described hereinafter, or any other medium from which acomputer can read. A digital file attachment to e-mail or otherself-contained information archive or set of archives is considered adistribution medium equivalent to a tangible storage medium. When thecomputer-readable media is configured as a database, it is to beunderstood that the database may be any type of database, such asrelational, hierarchical, object-oriented, and/or the like. Accordingly,the disclosure is considered to include a tangible storage medium ordistribution medium and prior art-recognized equivalents and successormedia, in which the software implementations of the present disclosureare stored. Computer-readable storage medium commonly excludes transientstorage media, particularly electrical, magnetic, electromagnetic,optical, magneto-optical signals.

A “coupler” or “fiber optic coupler” refers to the optical fiber devicewith one or more input fibers and one or several output fibers. Fibercouplers are commonly special optical fiber devices with one or moreinput fibers for distributing optical signals into two or more outputfibers. Optical energy is passively split into multiple output signals(fibers), each containing light with properties identical to theoriginal except for reduced amplitude. Fiber couplers have input andoutput configurations defined as M×N. M is the number of input ports(one or more). N is the number of output ports and is always equal to orgreater than M. Fibers can be thermally tapered and fused so that theircores come into intimate contact. This can also be done withpolarization-maintaining fibers, leading to polarization-maintainingcouplers (PM couplers) or splitters. Some couplers use side-polishedfibers, providing access to the fiber core. Couplers can also be madefrom bulk optics, for example in the form of microlenses and beamsplitters, which can be coupled to fibers (“fiber pig-tailed”).

The terms “analyze”, “determine”, “calculate” and “compute”, andvariations thereof, as used herein, are used interchangeably and includeany type of methodology, process, mathematical operation or technique.

A “laser emitter” refers to an end portion of a fiber or an opticalcomponent that emits laser light from a distal end of the cathetertowards a desired target or region, which typically comprises tissue.

An optical fiber (or laser active fiber) is a flexible, transparentfiber made of an optically transmissive material, such as glass (silica)or plastic, which functions as a waveguide, or “light pipe”, to transmitlight between the two ends of the fiber.

The term “biological material” includes any living cell or cells, andany biomolecule associated with a living cell or cells (i.e.,cell-based). Biological material includes both intracellularbiomolecules and extracellular biomolecules. Biological material mayinclude, for example, nucleic acids (i.e., RNA and DNA), amino acids(proteins and polypeptides), carbohydrates (e.g., sugars used forglycosylation), polysaccharides, lipids, and combinations thereof. Inthe context of the cardiovascular system, biological material includesbiomolecules associated with the various cell types that make up thevasculature (e.g., endothelial cells and smooth muscle cells), such ascell surface receptors.

The term “non-biological material” includes any material that is notassociated with a living cell or cells (i.e., non-cell-based).Non-biological material includes molecules typically found within anatherosclerotic occlusion and not the surrounding cells of thevasculature. Non-biological material found in atherosclerotic occlusionsinclude, for example, fat deposits (e.g., cholesterol monohydrate,cholesterol esters, and phospholipids), fibrous tissue (e.g., fibrin,proteoglycans, collagen), calcium deposits (e.g., calcium oxide, calciumcarbonate, calcium phosphates), and remnants of dead cells and cellulardebris.

The term “means” as used herein shall be given its broadest possibleinterpretation in accordance with 35 U.S.C., Section 112(f).Accordingly, a claim incorporating the term “means” shall cover allstructures, materials, or acts set forth herein, and all of theequivalents thereof. Further, the structures, materials or acts and theequivalents thereof shall include all those described in the summary ofthe invention, brief description of the drawings, detailed description,abstract, and claims themselves.

It should be understood that every maximum numerical limitation giventhroughout this disclosure is deemed to include each and every lowernumerical limitation as an alternative, as if such lower numericallimitations were expressly written herein. Every minimum numericallimitation given throughout this disclosure is deemed to include eachand every higher numerical limitation as an alternative, as if suchhigher numerical limitations were expressly written herein. Everynumerical range given throughout this disclosure is deemed to includeeach and every narrower numerical range that falls within such broadernumerical range, as if such narrower numerical ranges were all expresslywritten herein.

The preceding is a simplified summary of the disclosure to provide anunderstanding of some aspects of the disclosure. This summary is neitheran extensive nor exhaustive overview of the disclosure and its variousaspects, embodiments, and configurations. It is intended neither toidentify key or critical elements of the disclosure nor to delineate thescope of the disclosure but to present selected concepts of thedisclosure in a simplified form as an introduction to the more detaileddescription presented below. As will be appreciated, other aspects,embodiments, and configurations of the disclosure are possibleutilizing, alone or in combination, one or more of the features setforth above or described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated into and form a part of thespecification to illustrate several examples of the present disclosure.These drawings, together with the description, explain the principles ofthe disclosure. The drawings simply illustrate preferred and alternativeexamples of how the disclosure can be made and used and are not to beconstrued as limiting the disclosure to only the illustrated anddescribed examples. Further features and advantages will become apparentfrom the following, more detailed, description of the various aspects,embodiments, and configurations of the disclosure, as illustrated by thedrawings referenced below.

FIG. 1 shows an example apparatus for determining a type of a materialin a region within a vascular system of a patient and a distance to thematerial;

FIG. 2 is a top perspective view of a distal portion of a catheter, suchas a laser catheter;

FIG. 3 is an elevation view of a distal portion of a catheter, such as alaser catheter;

FIG. 4 is a cross-sectional perspective view of a distal portion of acatheter, such as a laser catheter;

FIG. 5 is a functional block diagram of the example apparatus of FIG. 1;

FIGS. 6A, 6B, 7A, and 7B are simplified views of reflected diffuseabsorbance and transmittance (DAAT) characteristics from the perspectiveof outputs of return fibers;

FIG. 8 illustrates a group of video frames of each of four returnfibers, including example intensities of a red channel, a green channel,and a blue channel for each of the return fibers and examplecorresponding indications of type of a material and/or distance to amaterial in a region within a vascular system of a patient;

FIGS. 8A-8C illustrate several magnified views of different portions ofthe video frame for one of the four return fibers of FIG. 8, includingseveral magnified views of the example intensities shown in FIG. 8 ofthe red, green, and blue channels for the fiber and several of theexample corresponding indications shown in FIG. 8 of type of a materialand/or distance to a material;

FIG. 9 is a flowchart of an example method for determining a type of amaterial in a region in a vascular system of a patient;

FIG. 10 is a flowchart depicting the steps of a surgical procedure usingan embodiment of the laser catheter of the present disclosure;

FIG. 11 illustrates an example use of displacement of source and/orreturn fibers to treat a broader area within a vascular system of apatient;

FIG. 12 illustrates an example use of an offset between ends of sourceand/or return fibers and a tip of a laser catheter to facilitatedetermination of properties of reflected light;

FIG. 13 illustrates an example portion of a human vasculature, such asan example portion of a blood vessel; and

FIGS. 13A-13C illustrate an example portion of a human vasculature, suchas an example portion of a blood vessel, with examples of positioningand/or use of a laser catheter for ablation.

DETAILED DESCRIPTION

Laser catheters typically transmit laser energy through optical fibershoused in a relatively flexible tubular catheter inserted into a bodylumen, such as a part of the vasculature, ureter, fallopian tube, andthe like to remove obstructions in the lumen. Catheters used for laserangioplasty and other procedures may have a central passageway or tubewhich receives a guide wire inserted into the body lumen (e.g.,vasculature) prior to catheter introduction. The guide wire facilitatesthe advancement and placement of the catheter to the selected portion(s)of the body lumen for laser ablation of tissue.

Examples of laser catheters or laser sheath are sold by theSpectranetics Corporation under the trade names ELCA™ and Turbo Elite™(each of which is used for coronary intervention or catheterization suchas recanalizing occluded arteries, changing lesion morphology, andfacilitating stent placement) and SLSII™ and GlideLight™ (which is usedfor surgically implanted lead removal). The working (distal) end of alaser catheter typically has a plurality of laser emitters, such as endsof source fibers, which emit energy and ablate the targeted tissue. Theopposite (proximal) end of a laser catheter typically has a fiber opticcoupler, which connects to a laser system or device or generatorincluding a light source. One such example of a laser system is theCVX-300 Excimer Laser System, which is also sold by the SpectraneticsCorporation.

Referring now to FIG. 1, an example apparatus 100 for determining a typeof a material in a region within a vascular system of a patient and adistance to the material (e.g., to a boundary of the material, asfurther discussed below) is shown in accordance with one embodiment ofthe present disclosure. The example apparatus 100 is illustrated asgenerally including a laser device 130, which may include a light sourcesuch as a laser (e.g., an excimer laser or any suitable laser), coupledto a proximal end of a laser catheter 170 by way of a coupler 140.

In another embodiment, a separate light source for purposes ofdetermining the type of the material and the distance to the material inthe region within the vascular system of the patient, which may at timesbe referred to as a diagnostic light source, may be included in thelaser device 130 and also coupled to the proximal end of the lasercatheter 170 by way of, for example, the coupler 140. The diagnosticlight source may be any suitable light source and need not be a laser.For example, the diagnostic light source may be or may include one ormore light-emitting diodes (LEDs), broadband light source(s) (e.g.,halogen light source(s)), xenon flash light source(s), etc. In such animplementation, the laser device 130 may still include at least onetreatment light source, which may also be referred to as a therapeuticlight source, such as a laser for ablating bodily material such asbuildup of plaque, calcium deposits, scar tissue, or the like. Thetherapeutic/treatment light source may be adjusted (e.g., in intensity,in distance from tissue, etc., as further described below) based on thedetermined type of the material in the region and/or the distance to thematerial in the region. It will be understood in light of the followingdisclosure that references herein to “light source” may include eitheror both of (e.g., collectively) the therapeutic/treatment light sourceand a diagnostic light source.

The laser catheter 170 is also connected to at least one controller 180by any suitable connection, such as, for example, by way of a wiredconnection via the coupler 140, a return connection portion 172, and ifdesired a device such as a USB microscope 175 to aid in producing imagesof the material in the region of the vascular system of the patientand/or other suitable data as discussed below. The laser catheter 170may also be connected to the at least one controller 180 by any othersuitable wired or wireless connection. While illustrated as a computingdevice, the at least one controller 180 may be implemented, for example,by executing suitable instructions on any suitable processor(s), by atleast one digital signal processor, by one or more application-specificintegrated circuits (ASICs), or by any other suitable hardware,firmware, or software implementation or any suitable combination of theexample implementations described above. In another embodiment, the atleast one controller 180 is connected to the laser device 130 andreceives and/or analyzes reflected light from a region within thevascular system of the patient, as further described below, after suchreflected light is received by the laser device 130. In yet anotherembodiment, the at least one controller 180 may be internal to the laserdevice 130.

As also illustrated in FIG. 1, a distal end of the laser catheter 170may be inserted into a patient 110, such as into the vasculature of thepatient 110. In some embodiments, the example apparatus 100 employs aplurality of fibers, such as optical fibers, as light guides that guidelaser light from the laser device 130 through the laser catheter 170 andtoward a target area or region within the vascular system of the patient110.

FIGS. 2 and 3 are a top perspective view and an elevation view,respectively, of a distal portion of a catheter, such as the examplelaser catheter 170, according to an embodiment of the presentdisclosure. As shown in the example of FIGS. 2 and 3, the distal portionof the laser catheter 170 may include an outer jacket 200 or sleeve, andmay include a distal end 202. The outer jacket 200 of the example ofFIGS. 2 and 3 comprises a flexible assembly with the ability to resistuser-applied forces such as torque, tension, and compression. Theproximal end (not shown) of the laser catheter 170 is attached to afiber optic coupler, such as the coupler 140 as shown in FIG. 1. Thelaser catheter 170 includes an outer jacket, inner band, and at leastone optical fiber similar to the configuration and orientation of suchcomponents as shown in FIGS. 2 and 3 and further described herein. Thedistal end 202 of the laser catheter 170 comprises a plurality ofoptical fibers, including at least one source fiber acting as a laseremitter or emitters, and at least one return fiber as further describedbelow. The energy emitted by the laser emitter(s) cuts, separates,and/or ablates the scar tissue, plaque build-up, calcium deposits, andother types of undesirable lesion or bodily material within the vascularsystem of the patient 110.

The distal end 202 of the laser catheter 170 may, in some embodiments,include a lumen 206. If the lumen 206 is included in the laser catheter170, a clinician may insert the laser catheter 170 into the vasculatureover a guidewire (not shown) through the lumen 206. It may, however, bepreferable for the laser catheter 170 to have a separate guidewirelumen. Incorporation of such a guidewire lumen is generally known to oneof ordinary skill in the art, and all such guidewire lumens within theknowledge of one skilled in the art are considered within the scope ofthe present disclosure. The lumen 206 may also be used to slide thelaser catheter 170 over an electrical lead in a lead removal procedure.The lumen may also include one or more fixed and/or removable conduit(s)for additional tools to assist in tissue removal or navigation, such asbut not limited to optical coherence tomography (OCT) catheters orintravascular ultrasound (IVUS) catheters. The additional tools mayassist in procedures associated with tissue removal or navigation suchas saline injection, suction, balloon deployment, and/or use ofinjectable contrast agents that can amplify the sensed optical contrastof targeted tissue(s) so as to improve the ability to correctlydiscriminate such tissue(s).

The aforementioned laser emitter(s), as further described below, may beprovided in a generally concentric configuration or in any othersuitable configuration such as an eccentric configuration. For example,the lumen 206, in embodiments where the laser catheter includes thelumen 206, may be provided substantially concentric with and interior tothe laser emitter(s) (and optical fiber(s)), or eccentric with respectto the laser emitter(s), thereby providing a potential conduit orpassageway for translocation of materials cut or ablated by the laseremitter(s).

Although FIGS. 2 and 3 illustrate the laser emitter(s) in a generallyconcentric configuration, those skilled in the art will appreciate thatthere are numerous other ways and configurations (e.g., eccentricconfigurations, as discussed above) in which to arrange at least onelaser emitter. Additionally, although these two figures illustrate anouter jacket 200 and a distal end 202, those of skill in the art willappreciate that distinct components need not be used, and the opticalfibers may be encapsulated within a single sleeve. Accordingly, FIGS. 2and 3, as well as FIG. 4 discussed below, are not intended to representthe only way that a laser catheter such as the laser catheter 170 may beconfigured and constructed, and all such configurations andconstructions within the knowledge of one skilled in the art areconsidered within the scope of this disclosure.

With continued reference to FIG. 3, a more particular exampleimplementation of the plurality of optical fibers is shown, according toan embodiment of the present disclosure. As shown in FIG. 3, theplurality of optical fibers may include at least one source fiber 300configured to supply light from a light source to a region within thevascular system of a patient so as to illuminate the region, and atleast one return fiber 302 configured to receive light reflected fromthe region, as further described below. In particular, the at least onesource fiber may include one or, as shown, a plurality of source fibers300. The at least one return fiber 302 may include one or, as shown, aplurality of return fibers 302 a, 302 b, 302 c, and 302 d. The pluralityof optical fibers may, if desired, be implemented such that fewer returnfibers than source fibers are used, and where the return fibers may havelarger cross-sectional area. The return fiber(s) 302 may be evenly orunevenly spaced around, for example, a lumen 206 within the lasercatheter 170. For example, if two return fibers 302 are used, the returnfibers 302 may be spaced 180 degrees apart from one another; if threereturn fibers 302 are used, the return fibers 302 may be spaced 120degrees apart from one another; and if four return fibers 302 are usedas shown in FIG. 3, the return fibers 302 may be spaced 90 degrees apartfrom one another. In other embodiments, the return fibers 302 may not beevenly spaced with respect to one another in manners such as the examplemanners provided above. The plurality of optical fibers may also includeat least one additional fiber 304 coupled to the light source (the lightsource being discussed above with respect to FIG. 1 and further belowwith respect to FIG. 5). The at least one additional fiber 304 may alsobe coupled, along with the source fiber(s) 300 and return fiber(s) 302,to the at least one controller 180 to enable the at least one controller180 to use information from the additional fiber(s) 304 regarding lightfrom the light source to determine an intensity of the light supplied bythe source fiber(s) 300.

FIG. 4 is a cross-sectional perspective view of a distal portion of alaser catheter, which may be used to implement the laser catheter 170,according to one embodiment of the present disclosure. As discussedabove, the laser catheter 170 may include a distal end 202 that may, insome embodiments, include the lumen 206. The distal end 202 may beoperable by a user, and the position of the distal end 202 is controlledby, for example, deflection means such as pullwires, shaping wires, andsimilar force-transmitting features controlled by the user at auser-proximal location of the laser catheter 170.

FIG. 5 is a functional block diagram of the example apparatus 100 fordetermining a type of a material in a region within a vascular system ofa patient and a distance to the material, according to one embodiment ofthe present disclosure. As in FIG. 1, the example apparatus 100 includesthe laser device 130, the coupler 140, the laser catheter 170, and theat least one controller 180. The laser device 130 includes a lightsource to which the laser catheter 170 is coupled by way of the coupler140. As shown in FIG. 5, the light source may take the form of a lasersource 500 (e.g., an excimer laser, etc.) or a diagnostic light source502 (e.g., an LED), where the laser source 500 is used for treatment(e.g., therapeutic purposes such as ablation). In another example, boththe laser source 500 and the diagnostic light source 502 may be used atdiffering times as desired or as best suited to a particular application(e.g., a particular region of the vasculature under analysis).

The laser catheter 170 includes at least one fiber bundle 504, which inturn may include the at least one source fiber 300 configured to supplylight from the light source to a region 506 within the vascular systemof a patient so as to illuminate the region 506. The region 506 maycomprise an electrical lead or leads as discussed above and, in somecases, buildup or deposit of unwanted material on or surrounding thelead(s). The at least one fiber bundle 504 may also include the at leastone return fiber 302 configured to receive light reflected from theregion 506 and the at least one additional fiber 304 to enabledetermination of the intensity of the light supplied by the sourcefiber(s) 300 from the light source. The at least one return fiber (e.g.,return fibers 302 a-302 d) may, for example, be configured to receivethe reflected light between pulses of laser light supplied from thelight source via the source fiber(s) 300. In another embodiment, the atleast one return fiber 302 may be configured to receive the reflectedlight from the region 506 within the vascular system of the patientwhere the light source is the diagnostic light source 502. The at leastone return fiber 302 may provide the reflected light to the coupler 140,which may in turn provide the reflected light to the at least onecontroller 180 for analysis as described below.

In various vascular intervention procedures, particularly in leadremoval procedures, it may be desirable to control the intensity oflight supplied via the source fiber(s) 300 to the region 506 for eachindividual fiber; that is, on a fiber-by-fiber basis. For example, atypical electrical lead passes through a portion of the superior venacava (SVC), and the SVC includes a relatively notable bend. In passingthe laser catheter 170 through that bend during a lead removalprocedure, it may be useful for a clinician to be able to control theamount of laser energy being emitted by the various fibers within thelaser ablation catheter. That is, the intensities in individual ones ofthe source fibers 300 may be varied with respect to one another undercontrol of the laser device 130. This may be done by the clinician orautomatically by the device itself. For example, source fibers 300interior to the bend in the SVC may not need an adjustment of theintensity of light passing therethrough from the light source, butsource fibers 300 on the outside portion of the bend in the SVC may needa reduction in the intensity of source light passing therethrough.

Similarly, there may be situations in which a clinician wishes tocontrol, or needs the ability to control, intensities of light suppliedby different ones of the source fibers 300 based on the intensities ofreflected light received by different ones of the return fibers 302(which reflected light is discussed in further detail below) in order toavoid vascular tissue tearing and other dangerous or undesirableresults. Accordingly, in an embodiment of the present disclosure,intensities of light supplied by various ones of the source fibers 300near a particular one of the return fibers 302 (e.g., return fiber 302a) may not be adjusted, while intensities of light supplied by variousones of the source fibers 300 near another particular one of the returnfibers 302 (e.g., return fiber 302 c) may be adjusted, such as when theintensity of reflected light received by the return fiber 302 c meetsparticular conditions such as falling within a color-specific range orranges of intensity, exceeding color-specific thresholds, etc.

Still further, in an embodiment of the present disclosure, theintensity/intensities of reflected light received by one or more of thereturn fibers 302 may be used to adjust the intensity/intensities oflight supplied by various ones of the source fibers 300 within the lasercatheter 170. As just several examples, the intensity of reflected lightreceived by one return fiber (e.g., return fiber 302 a) may be used toadjust the intensity of light supplied by source fibers 300 near the onereturn fiber, the intensity of light supplied by all source fibers 300,or the intensity of reflected light received by more than one of thereturn fibers 302 may be averaged or weighted in any other suitablemanner and similarly used to adjust the intensity of light supplied bysome or all of the source fibers 300. Any suitable use of theintensity/intensities of reflected light received by one or more of thereturn fiber(s) 302 to adjust the intensity of one or more of the sourcefiber(s) 300 may be implemented. Such suitable uses further include, byway of example, applications such as controlling therapeutic energybased on contacted tissue, e.g., increasing laser energy or selectingdifferent laser types for ablating calcified plaque and decreasingenergy for ablating soft plaque.

As shown in FIG. 5, the at least one controller 180 may include at leastone processor 508 coupled to at least one memory 510 and input/output(I/O) device(s) 512. The I/O device(s) 512 may include one or more keys,touch screens or other displays, dials, lights, audio input or outputdevices, a mouse, and/or any other suitable I/O device(s). The at leastone processor 508 may include laser device output logic 514 coupled tothe laser device 130 and configured to control at least one of a pulserate, a power level, and other characteristics of the optical energyoutput by the laser source 500 and/or the diagnostic light source 502.The at least one processor 508 may also include optical property sensinglogic 515 configured to receive the output of the coupler 140, after thecoupler 140 receives the reflected light from the at least one returnfiber 302 (e.g., return fibers 302 a-302 d), and to generate signalsindicative of sensed optical properties of the reflected light.

In one embodiment, the optical property sensing logic 515 may beimplemented in hardware and may include, for example, at least one of aspectrometer, filtered light sensor(s), charge-coupled device (CCD)array with suitable optics and/or filters, etc. The at least oneprocessor 508 may further include optical property determining logic 516coupled to the optical property sensing logic 515, and the opticalproperty determining logic 516 may be coupled to material typedetermining logic 518 and material distance determining logic 520 inorder to determine a type of a material in the region 506 within thevascular system of the patient and in order to determine a distance tothe material in the region 506, respectively.

Each of the laser device output logic 514 and other logic describedherein may be implemented as software by executing suitable instructionson, for example, the at least one processor 508, or by storingexecutable instructions on a computer-readable medium (e.g., in the atleast one memory 510), where the executable instructions are executableby at least one processor such as the at least one processor 508 tocause the at least one processor to perform the actions describedherein. The various logic described herein may also be implemented inany other suitable manner, such as but not limited to a hardwareimplementation or any suitable combination of the exampleimplementations described above. In the case of, for example, a hardwareimplementation, it will be appreciated from the disclosure herein thatthe various logic described may be physically distinct from the at leastone processor 508. Additionally, in some cases, one or more of the logicelements described herein may be implemented as or considered as asingle logic element, such as, for example, the optical property sensinglogic 515 and the optical property determining logic 516. For example,the optical property sensing logic 515 and the optical propertydetermining logic 516 may be implemented as or considered as a singlelogic element that senses optical properties of the reflected light,generates signals indicative of the sensed optical properties, anddetermines the optical properties based on the generated signals.

The reflected light received from the at least one return fiber 302 maybe indicative of at least one of a transmittance, a reflectance, anabsorbance, and a scattering coefficient of the region 506 within thevascular system of the patient. As understood by one skilled in the art,transmittance may be expressed as the percentage of incident light(electromagnetic radiation) on a sample (e.g., tissue in the patient'sbody) at a particular wavelength that is transmitted through the sample.Absorbance may be expressed as the percentage of incident light(electromagnetic radiation) on a sample at a particular wavelength thatis absorbed by the sample. Reflectance may be expressed as thepercentage of incident light (electromagnetic radiation) on a sample ata particular wavelength that is reflected by the sample. The reflectedlight received from the at least one return fiber 302 may also beindicative of at least one of a polarization of a tissue in the region506 and optical coherence tomography data associated with the materialin the region 506, and/or these and/or other suitable optical propertiesof the region 506 may be sampled and indicated by the output of the atleast one return fiber 302 to the coupler 140.

The output of the coupler 140, which may be a modified coupler so as tocouple both the at least one source fiber 300 and the at least onereturn fiber 302, and if desired the at least one additional fiber 304as well, to the laser device 130 and/or the at least one controller 180,may be provided (e.g., as an image or video frame) to the opticalproperty sensing logic 515 as described above. In another embodiment, acoupler separate from the coupler 140 (which separate coupler is notshown) may couple, for example, the at least one return fiber 302 and,in some cases, the at least one additional fiber 304 to, for example,the at least one controller 180.

The optical property sensing logic 515 may receive the output of thecoupler 140 so as to generate at least one signal indicative of sensedoptical property or properties of the reflected light. The at least onesignal generated by the optical property sensing logic 515 may beprovided to the optical property determining logic 516, which maydetermine at least one property (e.g., at least one optical property) ofthe region 506 based on the at least one signal provided by the opticalproperty sensing logic 515. The at least one property of the region 506may include at least one of a transmittance of the region 506, areflectance of the region 506, an absorbance of the region 506, ascattering coefficient of the region 506, and an intensity of thereflected light within a spectrum. For example, the optical propertysensing logic 515 and the optical property determining logic 516 may usechanges in intensity of reflected light to determine the reflectance ofthe region 506. Other example ways of receiving the output of thecoupler 140 so as to determine the at least one property of the region506 will be understood by those of skill in the art after understandingthe present disclosure.

The optical property determining logic 516 may send informationregarding the determined at least one property of the region 506 to thematerial type determining logic 518. In some embodiments, the opticalproperty determining logic 516 may also or alternatively sendinformation regarding the determined at least one property to thematerial distance determining logic 520. The material type determininglogic 518 may determine, based on the information from the opticalproperty determining logic 516, the type of the material in the region506. As just one example, the material type determining logic 518 mayanalyze the determined at least one property of the region 506 withinthe vascular system by analyzing diffuse absorbance and transmittance(DAAT) characteristics of the region 506 as determined by the opticalproperty determining logic 516 to determine that the type of thematerial in the region 506 comprises biological material and, moreparticularly, that the type of the material comprises one of blood ortissue.

In other embodiments, the analysis by the material type determininglogic 518 may further indicate that the type of the material in theregion is biological material, for example, a particular cell type orbiomolecule associated with the cells of a particular tissue, such asSVC tissue, which may be particularly useful in assisting a clinician inavoiding dangerous SVC tears when performing ablation using the lasercatheter 170. In still further examples, the material type determininglogic 518 may determine that the type of the material in the region 506comprises non-biological material, such as, for example, fat deposits(e.g., cholesterol monohydrate, cholesterol esters and phospholipids),fibrous tissue (e.g., fibrin, proteoglycans, collagen), calcium deposits(e.g., calcium oxide, calcium carbonate, calcium phosphates), andremnants of dead cells and cellular debris in the region 506, etc.

As discussed above, the optical property determining logic 516 may alsoor alternatively send the information regarding the determined at leastone property of the region 506 within the vascular system of the patientto the material distance determining logic 520. The material distancedetermining logic 520 may determine, based on the information from theoptical property determining logic 516, an indication of a distance tothe material in the region 506 within the vascular system. For example,the material distance determining logic 520 may cause the at least onecontroller 180 to generate an indication (e.g., via the I/O device(s)512) that the distance to the material in the region 506 is shorter thandesired based on the determined type of the material in the region(e.g., based on determining that the type of the material in the region506 is SVC tissue, the at least one controller 180 may generate anindication of a risk of causing an SVC tear given the distance to theSVC). The material distance determining logic 520, and/or the materialtype determining logic 518, may also determine whether the material inthe region 506 is a proper target for laser ablation (e.g., based on thetype of the material in the region 506 and/or the distance to thematerial in the region 506). For example, if the material distancedetermining logic 520 indicates that the laser catheter 170 is indangerously close contact with the SVC, the material distancedetermining logic 520 may determine that the material in the region 506is not a proper target for ablation.

The material type determining logic 518 and the material distancedetermining logic 520 may also or alternatively be configured to causethe at least one controller 180 to generate, such as via the I/Odevice(s) 512, an alert based on the determined type of the material inthe region 506 and/or the determined distance to the material. The alertmay, for example, prompt a clinician to adjust an intensity of, or poweroff, the light source (e.g., laser source 500 or diagnostic light source502).

In accordance with an embodiment of the present disclosure, the materialtype determining logic 518 and/or the material distance determininglogic 520 may analyze the information from the optical propertydetermining logic 516 (e.g., determined transmittance, reflectance,absorbance, and/or scattering coefficient of the region 506) withrespect to a library of information regarding different types ofmaterials and/or distances to materials in order to determine materialtype and/or indication of distance, respectively. The library ofinformation may, in one embodiment, be contained within the at least onememory 510, and may comprise any suitable executable instructions orother content within memory to allow the material type determining logic518 and/or the material distance determining logic 520 to determinematerial type in the region 506 and/or indication of distance to thematerial in the region 506. The information from the optical propertydetermining logic 516 regarding the determined at least one property ofthe region 506 may, for example, be compared against information in thelibrary to determine the type of the material in the region 506 and/orthe distance to the material.

Furthermore, in accordance with an embodiment of the present disclosure,the optical property determining logic 516 may receive the output of thecoupler 140 so as to determine at least one property of the region 506on a fiber-by-fiber basis. That is, the optical property determininglogic 516 may determine the at least one property individually for eachof the return fibers 302, thus allowing the determining of the type ofthe material in the region 506 and/or the indication of the distance tothe material in the region 506 to be performed/provided for eachindividual one of the fibers 302. Such individualized determinations maybe useful when, for example, the laser catheter 170 is contacting bloodor tissue at an angle and thus the characteristics of reflected light ateach of the return fibers 302 are different (see, e.g., discussion ofFIG. 7B below). Additionally, the I/O device(s) 512 may, for example,display per-fiber feedback in real time and/or in a visual arrangementthat corresponds to the geometric arrangement of the fibers at the tipof the laser catheter 170. In one embodiment, real-time visualizationsmay be displayed, on a per-fiber basis if desired, by overlaying thereal-time visualizations onto existing fluoroscopy displays.

FIGS. 6A, 6B, 7A, and 7B are simplified views of reflected diffuseabsorbance and transmittance (DAAT) characteristics from the perspectiveof, for example, a clinician viewing the outputs of the return fibers302, as understood by one skilled in the art in view of the presentdisclosure, based on the laser catheter 170 being in regions withdifferent types of materials and being at different distances (includingdifferent angles) to such types of materials. In particular, FIG. 6Aillustrates a view 600 of reflected DAAT characteristics as viewed fromthe outputs of return fibers 302 a-302 d when a catheter tip, such as atip of the laser catheter 170, is in an approximately ten millimeter(mm) deep pool of blood. FIG. 6B illustrates the slightly more visiblereflected DAAT characteristics, as indicated by cross-hatched lines notpresent in FIG. 6A, when the catheter tip is in a shallower (e.g.,approximately four mm) deep pool of blood. FIG. 7A illustrates theincreasingly visible reflected DAAT characteristics, as indicated bysolid lines not present in either of FIG. 6A or 6B, when the cathetertip is in full (e.g., normal) contact with tissue. FIG. 7B illustrates arelatively mixed visibility of reflected DAAT characteristics that maybe present when, for example, the catheter tip is in contact with planartissue at an angle (e.g., an approximately 15 degree angle).

Turning now to FIG. 8, as noted above with respect to FIG. 5, theoptical property determining logic 516 may determine at least oneproperty of the region 506 from the reflected light from the region 506,and the at least one property may include an intensity of the reflectedlight within a spectrum. In particular, as discussed above, the opticalproperty determining logic 516 may use changes in intensity of reflectedlight to determine the reflectance of the region 506. In one embodiment,the optical property determining logic 516 may apply pixel masks toimage or video frames corresponding to each of the return fibers 302 inorder to separate out red, green, and blue channel intensity valuesassociated with the reflected light for each return fiber 302, therebyanalyzing the reflected light from the region 506 to determine theintensity values. FIG. 8 illustrates a group 800 of video frames of eachof four return fibers 802, 804, 806, and 808, which may be the returnfibers 302 a-302 d previously discussed herein.

More specifically, the group 800 of video frames shows exampleintensities of a red channel 810, a green channel 812, and a bluechannel 814 for each of the return fibers 802, 804, 806, and 808 andexample corresponding indications of type of a material and/or distanceto a material. For example, along the horizontal (time) axis, indication816 shows that a catheter tip (e.g., a tip of laser catheter 170) iscontacting an exposed vessel within the vascular system of a patient.Indication 818 shows that the catheter tip is in blood; indication 820shows that the catheter tip is in the SVC; indication 822 shows that thecatheter tip is moving along the SVC; indications 824 and 826 show thatthe catheter tip is in blood; indication 828 may alert a clinician tomove or push the catheter to the left; indication 830 may alert theclinician to move or push the catheter to the right; indication 832 mayalert the clinician to move or push the catheter up; indication 834 mayalert the clinician to move or push the catheter down; and indication836 may alert the clinician that the catheter tip is in blood. It willbe appreciated upon review of the present disclosure that the waveformsof intensities of the red, green, and blue channels 810, 812, and 814,and the corresponding indicators 816-836, are not necessarily indicativeof the conditions that may exist in a particular application, as suchintensities and conditions may depend upon a number of factors such ascharacteristics of the catheter employed, fiber characteristics, etc.

FIGS. 8A-8C illustrate several magnified views of different portions ofthe video frame for one of the four return fibers of FIG. 8,specifically in this example the return fiber 808. The magnified viewsinclude magnified views of the example intensities shown in FIG. 8 ofthe red channel 810, the green channel 812, and the blue channel 814 forthe return fiber 808 and several of the corresponding indications shownin FIG. 8. In particular, in the example of FIG. 8A, a magnified view isshown of the portion of the video frame for the return fiber 808 nearthe indication 818 that the catheter tip is in blood. As shown in FIG.8A, the intensity of the red channel 810 may, for example, be greaterthan the intensities of both the green channel 812 and the blue channel814. In the example of FIG. 8B, a magnified view is shown of the portionof the video frame for the return fiber 808 near the indication 820 thatthe catheter tip is in the SVC. In the example of FIG. 8C, a magnifiedview is shown of the portion of the video frame for the return fiber 808near the indication 822 that the catheter tip is moving along the SVC.As shown in FIGS. 8A and 8B, the intensities of the red, green, and bluechannels may, for example, each be higher when the catheter tip is inthe SVC, as shown in FIG. 8B, as compared to when the catheter tip is inblood, as shown in FIG. 8A. Additionally, as shown in FIGS. 8B and 8C,the intensities of the red, green, and blue channels may, for example,each be higher when the catheter tip is in the SVC as compared to whenthe catheter tip is moving along the SVC. Furthermore, the intensitiesof the green channel 812 and the blue channel 814 may, for example, benotably lower when the catheter tip is moving along the SVC, bothcompared to the intensity of the red channel 810, when the catheter tipis moving along the SVC and compared to the intensities of the green andblue channels when the catheter tip is in the SVC.

FIG. 9 is a flowchart of an example method for determining a type of amaterial and an indication of a distance to the material in a region ina vascular system of a patient. Each of the method illustrated in FIG. 9and the method illustrated further below in FIG. 10 may be carried outby one or more suitably programmed controllers or processors executingsoftware (e.g., by the at least one controller 180). Each of the methodsmay also be embodied in hardware or a combination of hardware andhardware executing software. Suitable hardware may include one or moreapplication specific integrated circuits (ASICs), state machines, fieldprogrammable gate arrays (FPGAs), digital signal processors (DSPs),and/or other suitable hardware. Although the methods are described withreference to the illustrated flowcharts, it will be appreciated thatmany other ways of performing the acts associated with the methods maybe used. For example, the order of some operations may be changed, andsome of the operations described may be optional. Additionally, whilethe methods may be described with reference to the example apparatus100, it will be appreciated that the methods may be implemented by otherapparatus as well, and that the apparatus 100 may implement othersuitable methods.

As to FIG. 9, as shown in block 900, the method may include receiving anoutput of a coupler (e.g., receiving, by the at least one controller180, an output of the coupler 140) coupled to at least one return fiber(e.g., 302) that receives light reflected from a region (e.g., 506)within a vascular system of a patient after at least one source fiber(e.g., 300) has supplied light to the region.

As shown in block 902, the method may also include determining (e.g., bythe optical property determining logic 516) at least one property of theregion within the vascular system from the reflected light from theregion.

As shown in block 904, the method may also include determining (e.g., bythe material type determining logic 518) a type of a material in theregion within the vascular system based on determining the at least oneproperty from the reflected light.

As shown in block 906, the method may also include determining (e.g., bythe material distance determining logic 520) an indication of a distanceto the material in the region within the vascular system based ondetermining the at least one property from the reflected light. Themethod may then end and may be repeated as needed or desired.

FIG. 10 is a flowchart of an example method for determining a type of amaterial and an indication of a distance to the material in a region ina vascular system of a patient, and for controlling a light sourceand/or controlling laser catheter positioning accordingly. As shown inblock 1000, the method may include positioning a tip of a laser catheter(e.g., 170) adjacent to unwanted blockage and/or deposits, such as thosesurrounding an electrical lead or those in, for example, a peripheralartery.

As shown in block 1002, the method may also include supplying diagnosticlight to a region (e.g., 506) containing the unwanted blockage/depositsusing at least one source fiber (e.g., 300) of the laser catheter.

As shown in block 1004, the method may include receiving light reflectedfrom the region containing unwanted blockage/deposits using at least onereturn fiber (e.g., 302) of the laser catheter 170.

As shown in block 1006, the method may also include determining at leastone property (e.g., by the optical property sensing logic 515 receivingthe output of the coupler 140 and generating at least one signalindicative of a sensed property of the reflected light, and by theoptical property determining logic 516 determining the at least oneproperty based on the signal generated by the optical property sensinglogic 515) of the region containing the unwanted blockage/deposits fromthe reflected light.

As shown in block 1008, the method may include determining a type of amaterial in the region and/or an indication of a distance to thematerial in the region (e.g., by the material type determining logic 518and/or the material distance determining logic 520) based on determiningthe at least one property of the region.

As shown in block 1010, the method may also include generating anindication (e.g., by the I/O device(s) 512) that an intensity of thelight source is to be adjusted, that the light source is to be turnedoff, and/or that the laser catheter is to be moved further from thematerial in the region. Alternatively, an indication may be generatedthat the laser catheter is to be moved closer to the material in theregion. The indication may be generated based on the determination(s)made in block 1008.

As shown in block 1012, the method may also include controlling thelight source and/or controlling the positioning of the laser catheter170 based on the generated indication (e.g., block 1010). The method maythen end and may be repeated as needed or desired.

FIG. 11 illustrates an example of displacement of source and/or returnfibers to treat a broader area within a vascular system of a patient,such as to treat a broader area within the region 506, as compared towhen such displacement of source and/or return fibers is notimplemented. As shown in FIG. 11, the laser catheter 170 may, forexample, be in contact with a portion of tissue 1100. One of the sourcefibers 300 and one return fiber, in this example the return fiber 302 a,is also shown within the laser catheter 170. As shown in the example ofFIG. 11, one or both of an end portion 1102 of the source fiber 300 andan end portion 1104 of the return fiber 302 a may be capable of beingdisplaced at any suitable time during illumination via the source fiber300 and/or collection of light via the return fiber 302 a. Suchdisplacement may allow information to be gathered, by way of thereflected light as discussed above, from a broader (e.g., moreexpansive) area within the region 506 (e.g., from more of the portion ofthe tissue 1100), and/or may allow treatment of a broader area withinthe region 506 as compared to when such displacement is not used. Thedisplacement of the end portion 1102 and/or the end portion 1104 may beimplemented in any suitable manner, such as but not limited to actuationby resonant vibrations or static displacements via piezo-electric orlaser-induced thermal actuation. Additionally, it will be understoodthat the illustration in FIG. 11 is one example implementation ofdisplacement of, for example, the source fiber 300 and/or the returnfiber 302 a, and that other suitable ways of implementing suchdisplacement may also be employed.

FIG. 12 illustrates an example of an offset between ends of sourceand/or return fibers and a tip of a laser catheter to facilitatedetermination of properties of the reflected light. As shown in FIG. 12,the laser catheter 170 may, for example, be in contact with anotherexample portion of tissue 1200. One of the source fibers 300 and severalreturn fibers, such as the return fibers 302 a, 302 b, and 302 c areshown within the laser catheter 170 in FIG. 12. The ends of the sourcefiber 300 and the return fibers 302 a-302 c may be offset from the point(e.g., surface) at which the laser catheter 170 is in contact with theportion of the tissue 1200. Any suitable offsets may be used, and someoffsets may be the same, as in the case of the return fibers 302 a-302 cin the example of FIG. 12. Additionally, if desired, one or more fibersmay not be offset. The use of offsets may facilitate more accuratediffuse reflection measurements, which may, for example, result in moreaccurate reflected DAAT characteristics as discussed above with respectto, for example, FIGS. 6A, 6B, 7A, and 7B.

FIG. 13 illustrates an example portion of a human vasculature, such asan example portion 1300 of a blood vessel. The portion 1300 of the bloodvessel may include an endothelial cell layer 1302 and a buildup (ordeposit) 1304, which may be or may include plaque, between theendothelial cell layer 1302 and a vessel wall 1306. It will beunderstood from the present disclosure that in various embodiments, theportion 1300 of the blood vessel shown in FIG. 13 may be, may include,or may be included within the region 506 of the vascular system asdiscussed above. The buildup 1304 includes a fatty core 1308. It may benecessary or desirable to ablate the fatty core 1308, which may be ormay contain hardened plaque, without ablating other portions of thebuildup 1304. By removing (e.g., ablating) the fatty core 1308 withoutremoving other portions of the buildup 1304, more living layers oftissue may be spared from lasing, which may lessen inflammatory andimmune responses. As a result, the risk of restenosis may advantageouslybe reduced.

Through the use of techniques such as those described above to determinea type of a material in a region within the vascular system, and anindication of a distance to such material, selective ablation of thefatty core 1308 may be achieved. Based on a determined type of amaterial and/or indication of distance to such material, the buildup1304 and the fatty core 1308 may be identified and the at least onesource fiber 300 may ablate a portion of the buildup 1304 so as tocreate an entry path 1310 into the fatty core 1308. Lasing may thencause the fatty core 1308 to ablate, and the resulting ablated plaquemay pass through an exit path 1312. A guidewire 1314 may hold the lasercatheter 170 in a position so as to perform the ablation and so that theablated plaque that passes through the exit path 1312 is collected witha downstream occlusion filter 1316 that ensures, for example, that theablated plaque does not mix into the bloodstream of the patient.

FIGS. 13A-13C illustrate an example portion of a human vasculature, suchas an example portion 1350 of a blood vessel, with examples ofpositioning and/or use of a laser catheter for ablation. It will beunderstood from the present disclosure that in various embodiments, theportion 1350 of the blood vessel may be, may include, or may be includedwithin the region 506 of the vascular system as discussed above. Forexample, FIG. 13A shows that the example portion 1350 may include aportion of the endothelium 1302 in vasculature, a portion of the intima1352 in vasculature, and a portion of the media 1354 in vasculature. Abuildup including the fatty core (e.g., containing hardened plaque) 1308is shown in the intima 1352. The guidewire 1314 may position the lasercatheter 170 in preparation for ablation, with the downstream occlusionfilter 1316 positioned to collect ablated material in order to ensurethat, for example, the ablated material does not mix into thebloodstream of the patient. The endothelium 1356, the intima 1358, andthe media 1360 on an opposite wall of the portion 1300 of the bloodvessel are also illustrated for completeness.

As shown in FIG. 13B, the laser catheter 170 may be advanced, using,e.g., the guidewire 1314, into the intima 1352 so that the lasercatheter 170 is adjacent the fatty core 1308. As shown in FIG. 13C, thelaser catheter 170 may be further advanced into the fatty core 1308 forablation of the fatty core. By removing (e.g., ablating) the fatty core1308 without removing other portions of the intima 1352, more livinglayers of tissue may be spared from lasing, which may lesseninflammatory and immune responses. In particular, through the use oftechniques such as those described above to determine a type of amaterial in a region within the vascular system, and an indication of adistance to such material, selective ablation of the fatty core 1308 maybe achieved. As a result, the risk of restenosis may advantageously bereduced.

It will be appreciated that various modifications of the embodimentsherein may be made after review of and understanding of the presentdisclosure. For example, different fiber tip geometries may be used tochange the treatment and/or diagnostic areas as desired, and/or tocontrol the gathering of reflected light. Diagnostic light sourceintensity may also be varied to more accurately reveal geometricfeatures of tissues in some cases. Fluorescence and/or mitochondrialmarkers may be employed to discriminate tissue types, such as usingmitochondrial markers to distinguish between live tissue and scartissue. Force/strain measurements may be made using a diffractiongrating (e.g., a Bragg diffraction grating) along the laser catheter 170or its tip, or using interferometry-based microelectromechanical systems(MEMS) sensors. Force sensors may also be used to infer or determinetissue type, including whether tissue is comprised of biologicalmaterial or non-biological material.

It will be further appreciated upon review of the disclosure that theexample features and methods described herein thus allow ablation ofunwanted blockage, deposits, etc. in a peripheral artery or, in asimilar procedure, surrounding an electrical lead. In the case of anelectrical lead, the lead itself may then be removed.

A number of variations and modifications of the disclosure can be used.It would be possible to provide for some features of the disclosurewithout providing others. Furthermore, embodiments of systems andmethods according to the present disclosure may include and/or be usedin conjunction with any of the systems, devices, structures, and/ormethods described in U.S. patent application Ser. Nos. 13/800,651,13/800,675, 13/800,700, and/or 13/800,728, all of which were filed onMar. 13, 2013, the disclosures of which are hereby incorporated byreference in their entireties.

The present disclosure, in various aspects, embodiments, andconfigurations, includes components, methods, processes, systems and/orapparatus substantially as depicted and described herein, includingvarious aspects, embodiments, configurations, sub-combinations, andsubsets thereof. Those of skill in the art will understand how to makeand use the various aspects, aspects, embodiments, and configurations,after understanding the present disclosure. The present disclosure, invarious aspects, embodiments, and configurations, includes providingdevices and processes in the absence of items not depicted and/ordescribed herein or in various aspects, embodiments, and configurationshereof, including in the absence of such items as may have been used inprevious devices or processes, e.g., for improving performance,achieving ease and/or reducing cost of implementation.

The foregoing discussion of the disclosure has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the disclosure to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of thedisclosure are grouped together in one or more, aspects, embodiments,and configurations for the purpose of streamlining the disclosure. Thefeatures of the aspects, embodiments, and configurations of thedisclosure may be combined in alternate aspects, embodiments, andconfigurations other than those discussed above. This method ofdisclosure is not to be interpreted as reflecting an intention that theclaimed disclosure requires more features than are expressly recited ineach claim. Rather, as the following claims reflect, inventive aspectslie in less than all features of a single foregoing disclosed aspects,embodiments, and configurations. Thus, the following claims are herebyincorporated into this Detailed Description, with each claim standing onits own as a separate preferred embodiment of the disclosure.

Moreover, though the description of the disclosure has includeddescription of one or more aspects, embodiments, or configurations andcertain variations and modifications, other variations, combinations,and modifications are within the scope of the disclosure, e.g., as maybe within the skill and knowledge of those in the art, afterunderstanding the present disclosure. It is intended to obtain rightswhich include alternative aspects, embodiments, and configurations tothe extent permitted, including alternate, interchangeable and/orequivalent structures, functions, ranges or steps to those claimed,whether or not such alternate, interchangeable and/or equivalentstructures, functions, ranges or steps are disclosed herein, and withoutintending to publicly dedicate any patentable subject matter.

What is claimed is:
 1. An apparatus for determining a type of a materialin a region within a vascular system of a patient, the apparatuscomprising: a laser catheter coupled to a light source, the lasercatheter comprising: a distal end and a tip at the distal end; at leastone source fiber disposed at the tip and configured to supply light fromthe light source to a contact region within a vascular system of apatient so as to illuminate the contact region within the vascularsystem of the patient; and at least one return fiber disposed at the tipand configured to receive light reflected from the contact region withinthe vascular system of the patient, the reflected light being indicativeof diffuse absorbance and transmittance characteristics of the contactregion within the vascular system of the patient; and at least onecontroller comprising a processor executing: optical propertydetermining logic configured to separate the reflected light into aplurality of channels, determine an intensity value for each pluralityof channels and determine the diffuse absorbance and transmittancecharacteristics of the contact region within the vascular system of thepatient, wherein the optical property determining logic identifies achange in intensity value for each plurality of channels and creates awaveform for each plurality of channels, wherein each waveform isrepresentative of the intensity value over time; and material typedetermining logic configured to determine a type of a material in thecontact region within the vascular system based on receiving the changein intensity value for each plurality of channels from the opticalproperty determining logic, wherein the material type determining logicdetermines whether the contact region is blood or tissue.
 2. Theapparatus of claim 1, wherein the material type determining logic isfurther configured to analyze the determined diffuse absorbance andtransmittance characteristics with respect to a library of informationregarding different types of materials so as to determine the type ofthe material in the contact region within the vascular system.
 3. Theapparatus of claim 1, wherein the material type determining logic isfurther configured to determine, if the material type determining logicdetermines the contact region is tissue, a particular cell type for thetissue.
 4. The apparatus of claim 1, wherein the material typedetermining logic is further configured to determine that the type ofthe material in the contact region within the vascular system comprisesnon-biological material.
 5. The apparatus of claim 4, wherein thematerial type determining logic is further configured to determine thatthe non-biological material in the contact region within the vascularsystem comprises at least one of plaque or calcified tissue based on thediffuse absorbance and transmittance characteristics.
 6. The apparatusof claim 1, wherein the reflected light is further indicative of atleast one of a polarization of tissue in the contact region within thevascular system of the patient and optical coherence tomography dataassociated with the material in the contact region within the vascularsystem of the patient.
 7. The apparatus of claim 1, wherein the lasercatheter further comprises at least one additional fiber coupled to thelight source, and wherein the processor having at least an opticaldetermining logic is further configured to use received information fromthe at least one additional fiber to determine an intensity of the lightsupplied by the at least one source fiber from the light source.
 8. Theapparatus of claim 1, wherein the optical property determining logic isfurther configured to generate an indication that an intensity of alight source used for treatment in the contact region within thevascular system of the patient is to be adjusted or that the lightsource used for treatment is to be powered off based on the diffuseabsorbance and transmittance characteristics, and wherein the lightsource used for treatment in the contact region is one of the lightsource used to supply light to the contact region for determining thetype of the material in the contact region and a different light source.9. An apparatus for determining a type of a material in a region withina vascular system of a patient and a distance to the material, theapparatus comprising: a laser catheter coupled to a light source, thelaser catheter comprising: a distal end and a tip at the distal end; atleast one source fiber disposed at the tip and configured to supplylight from the light source to a contact region within a vascular systemof a patient so as to illuminate the contact region within the vascularsystem of the patient; and at least one return fiber disposed at the tipand configured to receive light reflected from the contact region withinthe vascular system of the patient, wherein the reflected light isindicative of diffuse absorbance and transmittance characteristics ofthe contact region; and at least one controller comprising a processorexecuting: optical property determining logic configured to separate thereflected light into a plurality of channels, determine an intensityvalue for each plurality of channels and determine at least one propertyof the contact region within the vascular system from the reflectedlight from the contact region within the vascular system, wherein theoptical property determining logic identifies a change in intensityvalue for each plurality of channels and creates a waveform for eachplurality of channels, wherein each waveform is representative of theintensity value over time; material type determining logic configured todetermine a type of a material in the contact region within the vascularsystem based on receiving the change in intensity value for eachplurality of channels from the reflected light based upon the opticalproperty determining logic, wherein the material type determining logicdetermines whether the contact region is blood or tissue; and distancedetermining logic configured to determine an indication of a distance tothe material in the contact region within the vascular system based ondetermining the at least one property from the reflected light basedupon the optical property determining logic.
 10. The apparatus of claim9, wherein the material type determining logic is further configured todetermine, if the material type determining logic determines the contactregion is tissue, a particular cell type of the tissue, and wherein thematerial type determining logic is further configured to determinewhether the contact region comprises non-biological material.
 11. Theapparatus of claim 10, wherein the processor is further configured togenerate an alert associated with use of a light source for treatment inthe contact region within the vascular system of the patient based onthe material type determining logic, wherein the light source used fortreatment in the contact region is one of the light source used tosupply light to the contact region and a different light source.
 12. Theapparatus of claim 9, wherein the material type determining logicdetermines the type of the material in the contact region based in parton a geometry at a tip of the at least one return fiber receiving thereflected light.
 13. The apparatus of claim 9, wherein the processor isfurther configured to determine, based on the material type determininglogic, whether the material in the contact region within the vascularsystem is a proper target for laser ablation.
 14. The apparatus of claim9, wherein the processor is further configured to determine anindication of a distance to a boundary of the material in the contactregion based on the distance determining logic.
 15. A non-transitorycomputer-readable medium comprising executable instructions that whenexecuted by one or more processors cause the one or more processors to:separate reflected light received from at least one return fiberdisposed at the tip of a laser catheter and into a plurality of channelsand determines an intensity value for each plurality of channelsseparate the reflected light into a plurality of channels, based on theat least one signal, wherein the reflected light is from a contactregion within a vascular system of a patient after illumination of thecontact region with light from a light source, wherein the reflectedlight is indicative of diffuse absorbance and transmittancecharacteristics of the contact region; determine an intensity value foreach plurality of channels; determine a change in intensity value foreach plurality of channels; create a waveform for each plurality ofchannels, wherein each waveform is representative of the intensity valueover time; generate, based on the waveform, at least one signalindicative of at least one property of the contact region within thevascular system; determine the at least one property of the contactregion within the vascular system, based on the waveform; and determinea type of a material in the contact region within the vascular systembased on determining the at least one property of the contact region,wherein the executable instructions when executed by one or more of theprocessors cause the one or more processors to determine whether thecontact region is blood or tissue.
 16. The non-transitorycomputer-readable medium of claim 15, further comprising executableinstructions that when executed by the one or more processors cause theone or more processors to determine, if the contact region is blood, anindication of a depth of the blood based on determining the at least oneproperty of the contact region within the vascular system.
 17. Thenon-transitory computer-readable medium of claim 15, further comprisingexecutable instructions that when executed by the one or more processorscause the one or more processors to generate, based on determining theat least one property of the contact region within the vascular system,at least one of: (i) an indication that an intensity of the light sourceis to be adjusted, (ii) an indication that the light source is to beturned off, (iii) an indication that a laser catheter comprising sourcefibers used for the illumination of the contact region within thevascular system and at least one return fiber used to receive thereflected light is to be moved further from the material in the contactregion within the vascular system, and (iv) an indication that the lasercatheter is to be moved closer to the material in the contact regionwithin the vascular system.